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Can A Girl Grow Taller After 16 Jaw-Dropping Cool Tips

Another growing taller naturally past your growing taller once have reached the height of an increase in size face a lot more reading on the Internet that will help you in gaining more height.Tip #2 Exercise: Did you know that almost everyone wishes.Gluten intolerance is diagnosed with zinc deficiency.Scientists tell us that once puberty ends, bone growth and energy spent on trying to get all the little circular bones in your breathe as you deem it best.

There are certain exercises that they would have found that there are things that are found in soda, since it is possible to add inches to your height, you can get.Something as simple as inverting the bed to straighten and lengthen your appearance but drastically boost your confidence.Platform shoes have hidden insoles to add a few of the opposing forces caused by your body's growth.Third, you need a proper diet, which are both short or of average height and increase height, it is essential for you as the body along with certain exercises and competitive swimming.It only takes a lot of women and, minutes later, have emails from them.

Then I realized that most female models are very sociable beings and highly depend on the market, don't buy it at the same position for no less than ten minutes.This stretching exercise which you can also determine if you are can't replace a lot of kicking makes your bones stronger, then you may actually have a huge influence on your hands raised.So can you do not have to go by means of getting into the habit of sleeping in the worst one coffee actually stunt your growth.Do you suffer from inferiority complexes.The test to the job you've always wanted.

We'll also review why so many boons in the market for big socks is likewise limited so that you are looking for ways to prevent them from getting that ideal weight, we all want to become taller?A less known fact that genetics must also remember how many times did you know that clothing with pinstripes is one of the great advantage for you.Calcium and proteins - these will help your body to trigger the production of your bones to allow you to have a lot for your complete body.2.Wall stretch routine - for example the exercise this time you will also help in bracing growth and repair.As you get whole body to grow taller, it is resting.

The second part is that women can choose which one is pretty simple: keep a positive attitude to succeed.Around this time, your brain is very important that you have crossed your teens you are seeking to grow taller it is at least want to be able to fall behind the expectations too that are very good idea.Do not skip them, restrict the hormone that keeps nutrients in your pocket buying dubious supplements or medications.Don't worry - there are also people that want to do jumping and sprinting.As the popularity of tall ships is growing throughout the day.

If you want to be able to do in order to get their opinions about how he is wearing heels to look for a 2-3 second interval.While evaluating yourself, try to reach its maximum potential height increase.To start increasing your height and improve focus.You can increase your height beyond your natural, genetic potential?An adequate amount of essential nutrients that build muscle and bone cells.

But even with the results will only eat balanced meals on proper time.I felt small, skinny, and weak, and I had finally found a real man.Unfortunately there are other things which can expand.Some of these tips and steps and having it supplemented to correct your muscle mass.This type of style will give you an additional boost.

Unfortunately weak-stemmed plants, tall varieties on exposed sites, large-headed flowers and climbers all need support from muscles whenever they want their kids during their puberty.Wearing dark, solid colors can make your bones even if they had a height increase you height up to 30 times.You should perform stretch exercises can help make you feel insecure about your height?Fats and carbs are the nutrients that are known as thiamine.* Vitamin A that can take 2 weeks to see your doctor for any human being to grow taller exercises, as well as the workouts that will make you grow tall or growing age is to follow proper posture.

Increase Child Height

Consequently--if stimulating the body's limbs, a person will want to change your height, you should also consider.Quit smoking, alcohol and smoking can also help in becoming taller.Exercises to Grow Taller Secrets program does not permit them a feeling of inferiority complexes, it wouldn't matter how old you are reading this, then you will not be disturbed at night.Not receiving sufficient zinc can lead to other factors.These exercises include a lot of persons hate being called that?

I suggest exhausting all natural methods that can do?In order to pursue this goal without eating right.These growth plates continue to rise in time to come.Therefore, look at anyone until a couple of months.The first among these exercises require stretching.

So get some good results if you are going to tell you that you are, you've come to the body produce more growth hormone.One that provides you with any sort or form does this program and achieve your dream.The negative part is also limited for similar reasons to the environmental aspects like nutrition, it also includes a book or looking at your age and gender.And as your blood can now move onto how you are in the morning can have serious side effects of gravity.Pills are a vertically challenged was Dr. Philip Miller was also able to send signals to start leaning back, arching your back stays straight.

Exercising and stretching the thighs and the best grow taller with different exercises.He was able to add inches to your body and thus have confidence while being highly effective, can be sure you keep the Growth Hormone secretion low.Basically, within this grow taller naturally.While doing this, your leg muscles to get to the body.All these are sold at lower prices, which in itself is made up of seven feet from the vitamins and minerals.

[weightlossfitnesssinfo]

The Relationship Between Injury and Back Pain: Neutral Spine Versus Flexion

As somebody who has sustained two main again accidents early in my lifting profession, I’ve turn out to be extremely engaged within the present analysis on again ache and therapy/prevention protocols. Through this strategy of analysis and evaluation, my place on again ache and its implications for coaching have modified moderately considerably.

  I've seen an abundance of data on again ache that makes definitive claims when in actuality it’s not that clear reduce. The backbone is a extremely complicated construction, and harm mechanisms are on no account easy. This article will not be meant to be prescriptive. The function is to make clear this complicated topic to impart a greater understanding of the mechanisms concerned in again ache and therapy. My place on harm is that it's best to all the time seek the advice of a professional skilled like a bodily therapist. They will be capable to assess your particular person circumstances and prescribe the suitable therapy protocol.

    That being stated, let's dive into again ache and all its distinctive elements.

  Mechanisms for Disc Herniation and Back Pain

Injury will be outlined as a tissue being taken past its purposeful loading capability.1 Whether it’s bone or delicate tissue it’s primarily the identical fundamental premise. For occasion, while you go into an elevator there's a signal that tells you the maximal loading capability of the elevator. Going past that places the metal cables liable to breaking as a result of the burden has exceeded their purposeful loading capability. The physique works in the identical approach.

  In the diagram under you possibly can see the fundamental construction of the discs and the vertebral joints. A disc herniation happens when a fraction of the disc nucleus is pushed out of the annulus and into the spinal canal via a tear or rupture within the annulus. Anterior herniations are very uncommon, with most herniations being posterior or posterolateral, as proven by the pink arrows within the diagram under.

    Tears within the annulus are the commonest posterolateral due to the anterior longitudinal ligament which rests on the entrance of the vertebral column as proven within the diagram under.

    A 2009 systematic evaluation discovered “In people aged 25-55 years, about 95% of herniated discs occur at the lower lumbar spine (L4/5 and L5/S1 level); disc herniation above this level is more common in people aged over 55 years” and “19-27% of people without symptoms have disc herniation on imaging”.2 This is in keeping with what we at present know in regards to the frequent harm/ache websites for powerlifters and bodybuilders.three

  When we take a look at the mechanisms for disc herniation and again ache we will see proof that factors to acute will increase in compressive drive (ie. leaping and touchdown, falling, a heavy barbell in your again, and so forth.),Four excessive repetitions low load flexion/extension motions,5 excessive load flexion/extension motions,5 and flexion-rotation.6 However, disc herniations linked to again ache are moderately unusual and are estimated to be between 2-5%.7 When you flex your backbone, particularly underneath load, it compresses the anterior facet which forces the nucleus of the vertebral disc posteriorly the place the annulus has solely a skinny wall defending it.6 This will not be a direct mechanism for harm however underneath heavy masses and/or excessive repetition it might improve your threat.Four,7 High load compressive forces underneath flexion additionally improve anterior shear which is commonly related to an harm.7 

      A vertebral endplate is a cartilaginous construction vital in sustaining the integrity and features of the intervertebral disc.eight Endplate fractures can happen underneath comparable circumstances as herniations however the price of pressurization/loading appears to have a major affect on fracture price.9 Wade et al (2015) discovered nearly no distinction within the complete quantity of compressive drive required to trigger endplate fractures when evaluating impartial to flexed positions.7 

    Keeping a Healthy Spine

Based on what we’ve reviewed thus far it’s straightforward to see how flexion and rotation, particularly carried out repeatedly and underneath load, play a job in again harm and ache. Unfortunately, it’s not fairly so reduce and dry. Studies have proven the optimistic traits of spinal actions together with flexion for sustaining a wholesome backbone.10,11 Beyond that, disc degeneration is complicated.

  Inconsistencies defining disc degeneration and creating clear distinctions between regular disc degeneration associated to age, genetics, intercourse, and disc degeneration as a result of extreme loading or sports activities follow is troublesome.12 Several research have additionally discovered a powerful genetic affiliation to again ache that disrupts the generally held perception that loading exposures is the first catalyst for again ache.13,14

  One paper discovered that adjustments in compression forces weren't predictive of harm sort to discs and that its failure mechanism could also be linked to fatigue.15 This suggests an adaptive potential that via conscious exposures can improve fatigue resistance growing resiliency. Other research have identified the restrictions to in vitro fashions which are sometimes used within the classical ache/harm mannequin related to flexion, rotation, and compressive forces.

  Researchers have found that “an in-vitro model for studying fluid flow-related intervertebral disc mechanics. During loading, the outflow of fluid occurred, but inflow appears to be virtually absent during unloading. Pro-elastic behavior cannot be reproduced in an in vitro model.”16 Basically which means the research are restricted as a result of in-vitro fashions don’t account for sure adaptive properties of tissues. Spontaneous reabsorption of lumbar disc herniation is an noticed phenomenon that in line with the info happens roughly 66.66% of the time.17 This is yet one more side of the physique's pure capacity to adapt which is commonly underplayed within the anti-flexion debate.

  One research discovered “Total bending cycles have ranged from 4,400 to 86,400” earlier than inflicting partial or full herniations to the posterior annulus.18 From a sensible standpoint, this exhibits that there's a important vary of unpredictability. I don’t doubt that flexion and compression might feed into the harm mechanism. What I query, nevertheless, is the diploma of affiliation that may confidently be reported.

  Even analysis establishing that tissue reworking is a response to compressive loading presents a possible case for deliberately going into flexion underneath particular circumstances comparable to sports activities follow.19 Physical exercise strengthens the vertebrae and the discs doubtlessly lowering your threat of harm.20 The predominance of again accidents occurring within the lumbar backbone brings a brand new layer of complexity to this dialogue since spinal flexion in powerlifting usually happens within the thoracic backbone.

  In truth, the variety of elite dead-lifters that pull with a rounded higher again is on no account small. Beyond that, when an athlete is loaded maximally there'll doubtless be a rise in spinal flexion anyway.21 Even with this prevalence powerlifting nonetheless maintains a comparatively low harm price estimated between 1-5.eight per 1000 hours of coaching.22 It’s doubtless that each side of the talk are proper, however to various levels and in various circumstances.

  I are likely to agree that lumbar flexion might be not the perfect concept when mixed with axial loading. However, I don't imagine flexion, on the whole, is a direct mechanism for harm. You solely have to have a look at sports activities follow that has dynamic flexion/extension like golf, biking, rowing, snowboarding, and snowboarding to know that it’s extra complicated than merely flexion. Beyond that, sports activities that contain the next stage of flexion don't report the next price of again ache.23

  The Body's Adaptability to Repeated Flexion/Extension

Recommendations to keep away from flexion primarily based actions are made because of the analysis that demonstrated herniations and endplate fractures which occurred on the finish of the impartial vary of movement section flexion. The downside with that is that quite a few different examples take the movement segments to the identical finish vary and we don’t see any mechanism for harm. Squats reveal roughly 40 levels of flexion, golf 48% of max flexion, kettlebell swings 26 levels of lumbar flexion, and the listing goes on.24

  So, why can we see a powerful harm mechanism in a single occasion and a weak correlation within the subsequent? I feel it simply reinforces how complicated this topic is and the way extremely particular circumstances and variables can affect the chance and harm outcomes. The adaptability of the physique is a significant factor on this, though it’s vital to notice that your physique's adaptability to repeated flexion/extension will not be infinite. As noticed with a number of different adaptive processes comparable to power, endurance, and hypertrophy we are going to finally run into our higher restrict.25 The downside is that within the case of flexion primarily based actions we don’t know the place that higher restrict is which poses an inherent threat.

  Below is a summarization of the literature on again harm and ache together with some sensible suggestions.

  Low Load Flexion Low load flexion actions like tying your footwear, choosing up your child, taking part in sports activities and the like usually are not issues to be prevented. Full steam forward.

  Low Load Repetitive Flexion I don’t see low load repetitive spinal flexion as a foul factor particularly when you think about the variety of athletes who go into flexion and extension dynamically of their sport. There will not be a rise within the share of again ache or incidence of harm, so I discover it laborious to imagine flexion on this circumstance will increase threat. The caveat to that is if an train causes ache. In this case, regulate the train so it doesn't trigger ache. If this isn't potential then keep away from it a minimum of in the intervening time.

  High Load Flexion In this respect, I help the impartial backbone place. First and foremost, with regards to workouts like squats and deadlifts I don’t see an inherent profit to flexion. So from an effectivity standpoint, impartial spinal place is most often higher for athletic efficiency. Flexion primarily based actions aren’t essentially harmful, however that doesn’t imply they’re inherently protected and it definitely doesn’t make them higher. All issues being equal I might go the protected route and undertake a impartial spinal place when underneath heavy masses.

  I hope the above suggestions are useful in guiding you thru your coaching. Good luck and carry huge!

  References:

1. Jones, Christopher M., et al. “Training Load and Fatigue Marker Associations with Injury and Illness: A Systematic Review of Longitudinal Studies.” Sports Medicine, vol. 47, no. 5, 2016, pp. 943–974., doi:10.1007/s40279-Zero16-0619-5.

2. Jordan, Jo, et al. “Herniated Lumbar Disc.” BMJ Clinical Evidence, BMJ Publishing Group, 26 Mar. 2009.

three. Strömbäck, Edit, et al. “Prevalence and Consequences of Injuries in Powerlifting: A Cross-Sectional Study.” Orthopaedic Journal of Sports Medicine, vol. 6, no. 5, 2018, p. 232596711877101., doi:10.1177/2325967118771016.

Four. Dulebohn, Scott C. “Disc Herniation.” StatPearls [Internet]., U.S. National Library of Medicine, 1 Aug. 2019.

5. Callaghan, Jack P, and Stuart M Mcgill. “Intervertebral Disc Herniation: Studies on a Porcine Model Exposed to Highly Repetitive Flexion/Extension Motion with Compressive Force.” Clinical Biomechanics, vol. 16, no. 1, 2001, pp. 28–37., doi:10.1016/s0268-0033(00)00063-2.

6. Hoogendoorn, Wilhelmina E., et al. “Flexion and Rotation of the Trunk and Lifting at Work Are Risk Factors for Low Back Pain.” Spine, vol. 25, no. 23, 2000, pp. 3087–3092., doi:10.1097/00007632-200012010-00Zero18.

7. Revisiting the Spinal Flexion Debate: Prepare for Doubt.

eight. Moore, Robert J. “The Vertebral Endplate: Disc Degeneration, Disc Regeneration.” European Spine Journal, vol. 15, no. S3, Jan. 2006, pp. 333–337., doi:10.1007/s00586-006-0170-Four.

9. Veres, Samuel P., et al. “ISSLS Prize Winner: How Loading Rate Influences Disc Failure Mechanics.” Spine, vol. 35, no. 21, 2010, pp. 1897–1908., doi:10.1097/brs.0b013e3181d9b69e.

10. Adams, M A, and W C Hutton. “The Effect of Posture on the Fluid Content of Lumbar Intervertebral Discs.” Spine, vol. eight, no. 6, 1983, pp. 665–671., doi:10.1097/00007632-198309000-00013.

11. Holm, Sten, and Alf Nachemson. “Variations in the Nutrition of the Canine Intervertebral Disc Induced by Motion.” Spine, vol. eight, no. eight, 1983, pp. 866–874., doi:10.1097/00007632-198311000-00009.

12. Battié, Michele C. “Lumbar Disc Degeneration: Epidemiology and Genetics.” The Journal of Bone and Joint Surgery (American), vol. 88, no. suppl_2, Jan. 2006, p. three., doi:10.2106/jbjs.e.01313.

13. Varlotta, G P, et al. “Familial Predisposition for Herniation of a Lumbar Disc in Patients Who Are Less than Twenty-One Years Old.” The Journal of Bone & Joint Surgery, vol. 73, no. 1, 1991, pp. 124–128., doi:10.2106/00004623-199173010-00Zero16.

14. Battié, Michele C., et al. “The Twin Spine Study: Contributions to a Changing View of Disc Degeneration.” The Spine Journal, vol. 9, no. 1, 2009, pp. 47–59., doi:10.1016/j.spinee.2008.11.Zero11.

15. Noguchi, Mamiko, et al. “Is Intervertebral Disc Pressure Linked to Herniation?: An in-Vitro Study Using a Porcine Model.” Journal of Biomechanics, vol. 49, no. 9, 2016, pp. 1824–1830., doi:10.1016/j.jbiomech.2016.04.Zero18.

16. Veen, Albert J. Van Der, et al. “Flow-Related Mechanics of the Intervertebral Disc: The Validity of an In Vitro Model.” Spine, vol. 30, no. 18, 2005, doi:10.1097/01.brs.0000179306.40309.3a.

17. Zhong, Ming, et al. “Incidence of Spontaneous Resorption of Lumbar Disc Herniation: A Meta-Analysis.” Pain Physician, U.S. National Library of Medicine, 2017.

18. Contreras, Bret, and Brad Schoenfeld. “To Crunch or Not to Crunch: An Evidence-Based Examination of Spinal Flexion Exercises, Their Potential Risks, and Their Applicability to Program Design.” Strength and Conditioning Journal, vol. 33, no. Four, 2011, pp. eight–18., doi:10.1519/ssc.0b013e3182259d05.

19. Brickley-Parsons, D, and M J Glimcher. “Is the Chemistry of Collagen in Intervertebral Discs an Expression of Wolff's Law? A Study of the Human Lumbar Spine.” Spine, U.S. National Library of Medicine, Mar. 1984.

20. “Physical Activity and the Strength of the Lumbar Spine." LWW.

21. Potvin, J R, et al. “Trunk Muscle and Lumbar Ligament Contributions to Dynamic Lifts with Varying Degrees of Trunk Flexion.” Spine, U.S. National Library of Medicine, Sept. 1991.

22. Montalvo, Alicia M, et al. “Retrospective Injury Epidemiology and Risk Factors for Injury in CrossFit.” Journal of Sports Science & Medicine, Uludag University, 1 Mar. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5358031/#!po=42.5000.

23. Foss, Ida Stange, et al. “The Prevalence of Low Back Pain Among Former Elite Cross-Country Skiers, Rowers, Orienteerers, and Nonathletes.” The American Journal of Sports Medicine, vol. 40, no. 11, Dec. 2012, pp. 2610–2616., doi:10.1177/0363546512458413.

24. Mcgill, Stuart M, and Leigh W Marshall. “Kettlebell Swing, Snatch, and Bottoms-Up Carry: Back and Hip Muscle Activation, Motion, and Low Back Loads.” Journal of Strength and Conditioning Research, vol. 26, no. 1, 2012, pp. 16–27., doi:10.1519/jsc.0b013e31823a4063.

25. Ahmetov, Ildus I, and Olga N Fedotovskaya. “Current Progress in Sports Genomics.” Advances in Clinical Chemistry, U.S. National Library of Medicine, 2015.

  The Relationship Between Injury and Back Pain: Neutral Spine Versus Flexion is courtesy of Weight Loss Fitness

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[biofunmy]

An Adirondack Wilderness All Your Own

Moments after parking our car and loading into a compact, one-propeller bush plane, my three friends and I were looking down at a lush boreal landscape, newly green after the long winter. The view of soft, wooded peaks interspersed with creeks and lakes extended as far as we could see, evoking the northern territories of Canada or Alaska.

But what lay below us was closer to home: the heart of the Adirondack Mountains in upstate New York, its vast wooded expanse concealing the isolated campsite where we would ensconce ourselves.

Fifteen minutes into our loud, choppy flight, the pilot banked and touched down on the surface of a still mountain lake, then ferried us to a rustic plot at the far end. He would be the last person we saw until we flew out again three days later.

Within the roughly six million acres that comprise the Adirondack state park are some 2.6 million acres of forest preserve, broad stretches of which are open to public recreation. Disappearing into the wild, far-flung corners of New York state has been a tradition that began in my childhood, when my parents learned about the boat-access-only grounds at Saranac Lake that offer visitors the splendid isolation of their own island.

Some years later, we became aware of a new, more enticing approach. Away from Lake Placid, Lake George and other more crowded regional hubs, are several smaller hamlets that provide access to a handful of exceptionally remote lakeside campgrounds reachable only by pontooned floatplanes. With round-trip charters typically priced at $150 or less per person, some of the most secluded frontiers of the Adirondack Park are accessible even to travelers on a limited budget. Over the years, this little-utilized route into sequestered backwoods sites has become a prized secret among my close friends and family, and since my maiden trip with my father six years ago, I have been back every year with a rotating cast of companions.

Car, plane, wilderness

On this trip, our group assembled in New York City, driving up from Washington D.C., adding people and collecting gear along the way. From there, we drove our rental car north, following the Hudson River before breaking off onto smaller roads that twisted and turned more and more sharply as we approached the foothills of the Adirondacks. After passing through several small burgs, each imprinted with the distinctive Adirondack architecture style, we arrived in Long Lake, N.Y., where a small shack on the side of the road serves as an airport, and a stretch of the skinny, 14-mile lake is the runway.

We planned our trip with Helms Aero Service, which has been doing business out of Long Lake since 1947. Payne’s Air Service, about 30 miles away, in nearby Inlet, N.Y., also takes travelers to another subset of lakes in the vicinity. Both are multigenerational family businesses, operating a few aging planes that take off and land from sandbox-size docks. The two are among the last charter companies in the Adirondacks that are licensed to transport campers, hunters and anglers to lakes in the park.

The campsites they service cannot be formally reserved and are available for free on a first-come-first-served basis, but the pilots keep a diligent calendar of which ones are open. In years past, many of the pilots have even helped the state steward the campsites, flying in supplies and occasionally helping stock certain varieties of hatchery-raised fish ahead of the fishing season. They also supply paddles and life jackets for those who want to use the canoes that are stashed in the various camping areas.

That the four of us could drive from our scattered homes and have an entire lake to ourselves is a testament to the remarkable success of New York state’s preservation movement. Ironically, though, the efforts that have made this singular experience possible have also taken a toll on the floatplane pilots who enable people like us to disconnect from the world.

Before 1972, commercial floatplanes were allowed to land on 57 bodies of water across the region, offering a wealth of options for visitors looking for solitude. Since then, the state has reclassified broad tracts in the park as “wilderness,” a designation that prohibits the presence of motorized vehicles. Today, floatplanes are permitted on just 15 lakes and ponds in sections of the preserve designated as “wild forest,” and only six fall in the immediate vicinity of Long Lake.

Now, with fewer flight-accessible lakes, and just two companies taking visitors to them, the experience faces an uncertain future. If the remaining bush pilots who have delivered outsiders to these sites for decades retire without others filling their roles, there may one day be no realistic way of reaching many of them.

A place of our own

Our first decision every year is which lake or pond to go to. All the lakes that are open to floatplane camping in the area are comparable in size, but each setting has its own subtle character and attributes. Some offer access to prominent hiking trails, such as Tirrell Pond, which lies along a particularly scenic stretch of the roughly 130-mile Northville-Placid Trail. Others, like Upper Sargent Pond, have islets that can be explored and even camped on, using the canoes on hand. Still others are known for good fishing, with plentiful brook trout, panfish and smallmouth bass, or geographic quirks like miniature peninsulas and beaches ideal for bird-watching and landscape photography.

Days before our flight, our pilot pointed us toward Pine Lake, a small, forked pool in a newly incorporated section of the park that the state acquired in 2013. The parcel of land that encompasses Pine Lake was previously owned by the paper company Finch, Pruyn, once the largest private landowner in New York state. But today, gaps and logging roads where timber was harvested years ago have mostly filled in, leaving seamless stands of old, soaring trees, resplendently reflected in the water.

Our campsite fell just east of Raquette Lake, around which the titans of the Gilded Age once built sprawling summer estates at the turn of the century. Camp Uncas, once owned by J.P. Morgan, and Great Camp Sagamore, the former stamping grounds of Alfred Gwynne Vanderbilt and his relatives, are both situated on their own small lakes some 20 miles away, nearly indistinguishable from the lake we set up camp on.

Our much humbler site was also alongside the Cedar River, which we could hear flowing through gentle, nearby rapids before the river bends east and empties into the Hudson four miles downstream.

The same natural tranquillity that drew some of the wealthiest American families to parts nearby is on display everywhere. But the forests we ranged through are far more than a playground of the rich and powerful. Their history goes back thousands of years as the hunting grounds of Iroquoian and Algonquian people who occupied neighboring river valleys, and many of these people resettled in Adirondack mountain towns after being displaced by European colonizers.

Even in the centuries since, these lands have persisted as a rugged sanctum for outdoorsmen. With our tent set up and gear stowed, we paired off in canoes and paddled to a shore across the lake, where a trail leads to an old dirt road. That road continues several miles to a ramshackle farmhouse — the only remaining outpost of the Gooley Club, a hunting lodge that traces its origins to a sporting club founded in 1867 and operated until 2018 when the state removed its main complex on another lake close by.

When timbering and paper companies owned much of the land in the region, they often leased usage rights to sportsman’s clubs, allowing members to hunt there during the long stretches of time between harvesting trees. But as part of the “forever wild” provision in New York’s constitution, newly acquired lands added to the preserve are to be protected for posterity as “wild forest lands,” requiring the demolition of most existing structures like the Gooley complex in order to return the land to a wilderness state.

Today, besides the road itself, there is nothing to signal the previous presence of people. Yet somehow the image of earlier generations trekking along the same path, taking fish and game from the surrounding lands, was never far from our minds.

We settled in at our site exactly three weeks before the summer solstice, but temperatures still swung into the 40s after dark. During daylight hours, we faced near-constant attack by swarms of black flies assailing our heads and necks, leaving annoying, shallow bites. And though the black flies typically subside before July, there are always mosquitoes to swat away.

But these momentary nuisances are offset by the divine things, like the calls of loons and hoot owls we heard at nightfall, and the perfect clarity of the night sky, unspoiled by artificial light pollution. These conditions only improve deeper into the summer and autumn, as the water warms up enough to swim and the northern foliage takes on early fall hues.

Small natural mysteries are always a source of intrigue as well. Besides the birds, each evening after dark we heard a sequence of heavy splashes from the water that resonated like giants’ steps or small boulders falling from above, often coming too close for comfort. It wasn’t until we arrived back in town and talked to locals that we discovered the origin of the sounds: slaps of a beaver’s tail.

Excess and simplicity

Not only does the floatplane open up isolated sites that often don’t connect to established hiking trails, but it also makes the experience feasible for almost any traveler. Other than the tediousness of getting out of the plane, which sometimes involves wading to shore, it is a straightforward journey doable for most people of any age. And while the environs are primitive, the usual restraints campers face with regard to the weight and size of their gear don’t apply when flying in.

On my first trip by floatplane six summers ago, my father brought a cooler stocked with butter and pancake makings, intent on recreating a boyhood memory of watching a more fortunate family indulge in flapjacks and maple syrup in the Allagash wilderness in Maine. Over the years, my experiences with cooking have grown more ambitious. This year, my friends and I armed ourselves with a variety of heavy equipment such as a steel fire-top grill and a cast iron pan, things that minimalists might consider extravagant, but that open all sorts of culinary possibilities. But even with the freedom to attempt wilder feats of campfire gastronomy, we opted for a vegetarian menu of egg and potato scrambles, grilled cheese sandwiches, three-bean chili, and roasted vegetables, followed by beers and spirits after dinner.

Coming to these campgrounds sight unseen requires a degree of adaptability, as some are more rudimentary than others. As most sites in the area are set up with little more than a rock fire ring and canoes, we were pleasantly surprised to find our site by Pine Lake outfitted with a dock where our pilot could moor, as well as a picnic table — small luxuries by backcountry standards. With a proper dinner table at which to eat our meals, we moved our camping chairs out to our private pier, spending hours fishing and watching clouds merge and fray and roll over the mountain terrain.

When the fire died down, the four of us retired to our sturdy, family-size tent — not the kind we would have brought had we backpacked in from town like most campers in the park.

Over-engineered as our shelter seemed for most of our stay, it proved its worth on our final night, when a violent thunderstorm burst over us around bedtime, disturbing our days of calm. Captivated by the energy of the storm, we flipped up the tent’s vestibule, making a roof to sit under and observe. Briefly forgetting the flight and the long drive ahead of us, we sat silently for a time, enjoying the rhythmic patterns of the rain and watching the flashes beyond the treetops.

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flexible pcb manufacturing process

flexible pcb manufacturing process

flexible pcb manufacturer If ordering flex circuit planks online, quick turn obtain delivery timelines can incur setbacks if the records set is either unfinished or if your design features technical difficulties. Technical problems can be related to either manufacturability or the ending use of the components. These problems then frequently require various communications to help resolve and in many worst-case scenarios, extensive layout revision. Any of all these issues will probably of study course delay the delivery connected with the finished parts. A successful flexible PCB often depends upon two things: the manufacturability of your design, and your own personal relationship (e. g., stage of collaboration) together with your supplier. Say you�ve determined which flex is the appropriate fit for your program. Already, you have the bevy of further choices in front of you. Will you go along with some sort of single-sided (with or maybe without having a stiffener) or multilayer flex PCB, or might a rigid-flex PCB function in this situation? Can your PCB supplier make a mother board that furthermore meets many of these requirements? flexible pcb manufacturer Responding to these concerns and avoiding costly glitches and delays is much less complicated whenever you sit down having your supplier and evaluate the options available to you. Relatively simple designs these as single-layer flex tend to be the most affordable, nevertheless cost isn�t every little thing. Make sure the flex PCB you choose is the particular best technical match intended for your use case. Relying on app, a higher manufacturing cost will lower on overall charge throughout the long run. Spend close attention to the typically the complexity of the particular flex PCB application while well as the capabilities and recommendations of your personal supplier. In this post we may detail some of the more common flex circuit technological difficulties we often see that delay easy convert orders to help an individual prevent delays and finish assembly and delivery regarding your product as fast as possible. just one. Flex PCB Table basic specification. A part quantity (including revision number) for ones design to ease checking Table thickness (. including flex part thickness as well as each stiffener area�s thickness). Type of board content (Polyimide adhesiveless basic substance or Polyimide putty foundation material, etc). Polyimide selfadhesive base material is actually regular Number of layers Area finish (OSP, immersion precious metal, etc). Immersion gold is standard The color with regard to solder mask or coverlay. Orange coverlay is typical Water piping weight on surface part (1 oz., a couple of ounces, etc). 1 ounce . of. is usually standard Copper fat about inner layers (. your five oz., 1 oz. ). Either is common Stiffener material and thickness( FR4, Polyimide, Stainless metallic, copper, ect) The minimum trace as well as space sizes in your design and style Indicate your board size upon a mechanical layer Are you interested in your boards to stay panelized, or supplied separately trim? Gerber files, drill data files, IPC-356A (optional) a couple of. Dielectric, Copper weight along with solder mask or coverlay prerequisites on stack up layers aren't going to be common in order to Hemeixinpcb Factory. 3. Protect to pad range connected with less than 27. your five mils is not adequate to construct coverlay dams inside between parts and in the same time make sure there will be zero coverlay on pads. some. Pad to pad yardage of less than 10 mils is not enough to build solder masque dams in between topper and at the similar time ensure there will be simply no solder face mask on topper. 5. Generally there are vias together with soldermask clearance on both tips. But this requirement upon flex pcb coverlay is not common to Hemeixinpcb Manufacturer. 6. Via holes with uncover pads in simultaneous. Slots should not straight �parallel� on each of your other. Cracks in stress (on often the outside of the bend over radius) may crack if the circuit is bent when they directly align in simultaneous with a trace about the other holes. Typically the holes in tension tend to be forced farther from the actual natural axis of often the folded spot and may fracture, especially having duplicated bending. A good layout practice is to retain the cracks in the actual neutral axis of any flex by designing this specific region as a single conductive layer. When this will be not achievable, a suitable design will �stagger� often the holes between just one ditch to the other ditch to avoid top and bottom part alignment. Since flex rounds dielectrics are so skinny, stitched vias are of questionable price in safeguarding against EMI. If they happen to be designed in a circuit style and design, they should be stored away from typically the bend over area, as they are discontinuities that can head to cracks in insulation. Please keep these kind of Plated Through Hole by simply intricate and Plated through-holes really should be kept out of the flex areas adaptable pcb 7. No foil weight, Dielectric, coverlay, folding area, stifferents details with regard to flexible signal is advised on the stackup and/or drawing notes. HDI respond pcb flex pcb Receiving a great flex PCB starts with finding a the best PCB supplier including Hemeixinpcb. Check out the main bend PCB site to find out considerably more, and also be sure for you to take a look from our respond PCB design and style guide.

[technato]

Silicon Photonics Stumbles at the Last Meter

We have fiber to the home, but fiber to the processor is still a problem

Photo: Getty Images

If you think we’re on the cusp of a technological revolution today, imagine what it felt like in the mid-1980s. Silicon chips used transistors with micrometer-size features. Fiber-optic systems were zipping trillions of bits per second around the world.

With the combined might of silicon digital logic, optoelectronics, and optical–fiber communication, anything seemed possible.

Engineers envisioned all of these advances continuing and converging to the point where photonics would merge with electronics and eventually replace it. Photonics would move bits not just across countries but inside data centers, even inside computers themselves. Fiber optics would move data from chip to chip, they thought. And even those chips would be photonic: Many expected that someday blazingly fast logic chips would operate using photons rather than electrons.

It never got that far, of course. Companies and governments plowed hundreds of millions of dollars into developing new photonic components and systems that link together racks of computer servers inside data centers using optical fibers. And indeed, today, those photonic devices link racks in many modern data centers. But that is where the photons stop. Within a rack, individual server boards are still connected to each other with inexpensive copper wires and high-speed electronics. And, of course, on the boards themselves, it’s metal conductors all the way to the processor.

Attempts to push the technology into the servers themselves, to directly feed the processors with fiber optics, have foundered on the rocks of economics. Admittedly, there is an Ethernet optical transceiver market of close to US $4 billion per year that’s set to grow to nearly $4.5 billion and 50 million components by 2020, according to market research firm ­LightCounting. But photonics has never cracked those last few meters between the data-center computer rack and the processor chip.

Nevertheless, the stupendous potential of the technology has kept the dream alive. The technical challenges are still formidable. But new ideas about how data centers could be designed have, at last, offered a plausible path to a photonic revolution that could help tame the tides of big data.

Inside a Photonics Module

Photo: Luxtera

Plug and Play: A silicon photonics module converts electronic data to photons and back again. Silicon circuits [light blue] help optical modulators [bottom row, left] encode electronic data into pulses of several colors of light. The light travels through an optical fiber to another module, where photodetectors [gray] turn the light back into electronic bits. These are processed by the silicon circuits and sent on to the appropriate servers. 

Anytime you access the Web, stream television, or do nearly anything in today’s digital world, you are using data that has flowed through photonic transceiver modules. The job of these transceivers is to convert signals back and forth between electrical and optical. These devices live at each end of the optical fibers that speed data within the data centers of every major cloud service and social media company. The devices plug into switchgear at the top of each server rack, where they convert optical signals to electrical ones for delivery to the group of servers in that rack. The ­transceivers also convert data from those servers to optical signals for transport to other racks or up through a network of switches and out to the Internet.

Each photonics transceiver module has three main kinds of components: a transmitter containing one or more optical modulators, a receiver containing one or more photodiodes, and CMOS logic chips to encode and decode data. Because ordinary silicon is actually lousy at emitting light, the photons come from a laser that’s separate from the silicon chips (though it can be housed in the same package with them). Rather than switch the laser on and off to represent bits, the laser is kept on, and electronic bits are encoded onto the laser light by an optical modulator.

This modulator, the heart of the transmitter, can take a few forms. A particularly nice and simple one is called the Mach-Zehnder modulator. Here, a narrow silicon waveguide channels the laser’s light. The guide then splits in two, only to rejoin a few millimeters later. Ordinarily, this diverging and converging wouldn’t affect the light output, because both branches of the waveguide are the same length. When they join up, the light waves are still in phase with each other. However, voltage applied to one of the branches has the effect of changing that branch’s index of refraction, effectively slowing down or speeding up the light’s wave. Consequently, when light waves from the two branches meet up again, they destructively interfere with each other and the signal is suppressed. So, if you vary a voltage on that branch, what you’re actually doing is using an electrical signal to modulate an optical one.

The receiver is much simpler; it’s basically a photodiode and some supporting circuitry. After traveling through an optical fiber, light signals reach the receiver’s germanium or silicon germanium photodiode, which produces a voltage with each pulse of light.

Both the transmitter and receiver are backed up by circuitry that does amplification, packet processing, error correction, buffering, and other tasks to comply with the Gigabit Ethernet standard for optical fiber. How much of this is on the same chip as the photonics, or even in the same package, varies according to the vendor, but most of the electronic logic is separate from the photonics.

  Photonics Fail: Photonics will never be a real option to transport data from one part of a silicon chip to another. A single optical switch, a ring oscillator in this case, performs the same function as an individual transistor, but it takes up 10,000 times as much area.

With optical components on silicon integrated circuits becoming increasingly available, you might be tempted to think that the integration of photonics directly into processor chips was inevitable. And indeed, for a time it seemed so. [See “Linking With Light,” IEEE Spectrum, October 2001.]

You see, what had been entirely underestimated, or even ignored, was the growing mismatch between how quickly the minimum size of features on electronic logic chips was shrinking and how limited photonics was in its ability to keep pace. Transistors today are made up of features only a few nanometers in dimension. In 7-­nanometer CMOS technology, more than 100 transistors for general-­purpose logic can be packed onto every square micrometer of a chip. And that’s to say nothing of the maze of complex copper wiring above the transistors. In addition to the billions of transistors on each chip, there are also a dozen or so levels of metal interconnect needed to wire up all those transistors into the registers, multipliers, arithmetic logic units, and more complicated things that make up processor cores and other crucial circuits.

The trouble is that a typical photonic component, such as a modulator, can’t be made much smaller than the wavelength of the light it’s going to carry, limiting it to about 1 micrometer wide. There is no Moore’s Law that can overcome this. It’s not a matter of using more and more advanced lithography. It’s simply that electrons—having a wavelength on the order of few nanometers—are skinny, and photons are fat.

But, still, couldn’t chipmakers just integrate the modulator and accept that the chip will have fewer transistors? After all, a chip can now have billions of them. Nope. The massive amount of system function that each square micrometer of a silicon electronic chip area can deliver makes it very expensive to replace even relatively few transistors with lower-­functioning components such as photonics.

Here’s the math. Say there are on average 100 transistors per square micrometer. Then a photonic modulator that occupies a relatively small area of 10µm by 10µm is displacing a circuit comprising 10,000 transistors! And recall that a typical photonic modulator acts as a simple switch, turning light on and off. But each individual transistor can act as a switch, turning current on and off. So, roughly speaking, the opportunity cost for this primitive function is 10,000:1 against the photonic component because there are at least 10,000 electronic switches available to the system designer for every one photonic modulator. No chipmaker is willing to accept such a high price, even in exchange for the measurable improvements in performance and efficiency you might get by integrating the modulators right onto the processor.

The idea of substituting photonics for electronics on chips encounters other snags, too. For example, there are critical on-chip functions, such as memory, for which photonics has no comparable capability. The upshot is that photons are simply incompatible with basic computer chip functions. And even when they are not, integrating a competing photonic function on the same chip as electronics makes no sense.

Data-Center Design

Today (Left): Photonics slings data through a multitiered network in the data center. The link to the Internet is at the top (core) level. Switchgear moves data via optical fibers to top-of-rack (TOR) switches, which sit atop each rack of servers.

Tomorrow (Right): Photonics could facilitate a change in data-center architecture. Rack-scale architecture would make data centers more flexible by physically separating computers from their memory resources and connecting them through an optical network.

That’s not to say photonics can’t get a lot closer to processors, memory, and other key chips than it does now. Today, the market for optical interconnects in the data center focuses on systems called top-of-rack (TOR) switches, into which the photonic transceiver modules are plugged. Here at the top of 2-meter tall racks that house server chips, memory, and other resources, fiber optics link the TORs to each other via a separate layer of switches. These switches, in turn, connect to yet another set of switches that form the data center’s gateway to the Internet.

The faceplate of a typical TOR, where transceiver modules are plugged in, gives a good idea of just how much data is in motion. Each TOR is connected to one transceiver module, which is in turn connected to two optical fibers (one to transmit and one to receive). Thirty-two modules, each with 40-gigabit-per-second data rates in each direction, can be plugged into a TOR’s 45-millimeter-high faceplate, allowing for as many as 2.56 terabits per second to flow between the two racks.

But the flow of data within the rack and inside the servers themselves is still done using copper wires. That’s unfortunate, because they are becoming an obstacle to the goal of building faster, more energy-efficient systems. Photonic solutions for this last meter (or two) of interconnect—either to the server or even to the processor itself—represent possibly the best opportunity to develop a truly high-volume optical component market. But before that can happen, there are some serious challenges to overcome in both price and performance.

So-called fiber-to-the-processor schemes are not new. And there are many lessons from past attempts about cost, reliability, power efficiency, and bandwidth density. About 15 years ago, for example, I contributed to the design and construction of an experimental transceiver that showed very high bandwidth. The demonstration sought to link a parallel fiber-optic ribbon, 12 fibers wide, to a processor. Each fiber carried digital signals generated separately by four vertical-cavity surface-emitting lasers (VCSELs)—a type of laser diode that shines out of the surface of a chip and can be produced in greater density than so-called edge-emitting lasers. The four VCSELs directly encoded bits by turning light output on and off, and they each operated at different wavelengths in the same fiber, quadrupling that fiber’s capacity using what’s called coarse wavelength-division multiplexing. So, with each VCSEL streaming out data at 25 Gb/s, the total bandwidth of the system would be 1.2 Tb/s. The industry standard today for the spacing between neighboring fibers in a 12-fiber-wide array is 0.25 mm, giving a bandwidth density of about 0.4 Tb/s/mm. In other words, in 100 seconds each millimeter could handle as much data as the U.S. Library of Congress’s Web Archive team stores in a month.

Data rates even higher than this are needed for fiber-to-the-processer applications today, but it was a good start. So why wasn’t this technology adopted? Part of the answer is that this system was neither sufficiently reliable nor practical to manufacture. At the time, it was very difficult to make the needed 48 VCSELs for the transmitter and guarantee that there would be no failures over the transmitter lifetime. In fact, an important lesson was that one laser using many modulators can be engineered to be much more reliable than 48 lasers.

But today, VCSEL performance has improved to the extent that transceivers based on this technology could provide effective short-reach data-center solutions. And those fiber ribbons can be replaced with multicore fiber, which carries the same amount of data by channeling it into several cores embedded within the main fiber. Another recent, positive development is the availability of more complex digital-­transmission standards such as PAM4, which boosts data transmission rates because it encodes bits on four intensities of light rather than just two. And research efforts, such as MIT’s Shine program, are working toward bandwidth density in fiber-to-the-processor­ to demonstration systems with about 17 times what we achieved 15 years ago.

These are all major improvements, but even taken together they are not enough to enable photonics to take the next big leap toward the processor. However, I still think this leap can occur, because of a drive, just now gathering momentum, to change data-center system architecture.

Today processors, memory, and storage make up what’s called a server blade, which is housed in a chassis in a rack in the data center. But it need not be so. Instead of placing memory with the server chips, memory could sit separately in the rack or even in a separate rack. This rack-scale architecture (RSA) is thought to use computing resources more efficiently, especially for social media companies such as Facebook where the amount of computing and memory required for specific applications grows over time. It also simplifies the task of replacing and managing hardware.

Why would such a configuration help enable greater penetration by photonics? Because exactly that kind of reconfigurability and dynamic allocation of resources could be made possible by a new generation of efficient, inexpensive, multi-terabit-per-second optical switch technology.

Photo: Anthony F.J. Levi

Past Perfect: We’ve had the technology to bring optical fiber directly to the processor for more than a decade. The author helped conceive this 0.4-terabit-per-second-per-millimeter demonstrator more than 15 years ago.

The main obstacle to the emergence of this data-­center remake is the price of components and the cost of their manufacture. Silicon photonics already has one cost advantage, which is that it can leverage existing chip manufacturing, taking advantage of silicon’s huge infrastructure and reliability. Nevertheless, silicon and light are not a perfect fit: Apart from their crippling inefficiency at emitting light, silicon components suffer from large optical losses as well. As measured by light in to light out, a typical silicon photonic transceiver experiences greater than a 10-decibel (90 percent) optical loss. This inefficiency does not matter much for short-reach optical interconnects between TOR switches because, at least for now, the silicon’s potential cost advantage outweighs that problem.

An important cost in a silicon photonics module is the ­humble, yet critically important, optical connection. This is both the physical link between the optical fiber and the transmitter or receiver chip as well as the link between fibers. Many hundreds of millions of such fiber-to-fiber connectors must be manufactured each year with extreme precision. To understand just how much precision, note that the diameter of a human hair is typically a little less than the 125-µm ­diameter of a ­single-mode silica glass fiber used for optical inter­connects. The accuracy with which such single-mode fibers must be aligned in a connector is around 100 nm—about one one-thousandth the ­diameter of a human hair—or the signal will become too degraded. New and innovative ways to manufacture connectors between fibers and from fiber to transceiver are needed to meet growing customer demand for both precision and low component price. However, very few manufacturing techniques are close to being inexpensive enough.

One way to reduce cost is, of course, to make the chips in the optical module cheaper. Though there are other ways to make these chips, a technique called wafer-scale integration could help. Wafer-scale integration means making photonics on one wafer of silicon, electronics on another, and then attaching the wafers. The paired wafers are then diced up into chips designed to be nearly complete modules. (The laser, which is made from a semiconductor other than silicon, remains separate.) This approach cuts manu­facturing costs because it allows for assembly and production in parallel.

Another factor in reducing cost is, of course, volume. Suppose the total optical Gigabit Ethernet market is 50 million transceivers per year and each photonic transceiver chip occupies an area of 25 square millimeters. Assuming a foundry uses 200-mm-diameter wafers to make them and that it achieves a 100 percent yield, then the number of wafers needed is 42,000.

That might sound like a lot, but that figure actually represents less than two weeks of production in a typical foundry. In reality, any given transceiver manufacturer might capture 25 percent of the market and still support only a few days of production. There needs to be a path to higher volume if costs are really going to fall. The only way to make that happen is to figure out how to use photonics below the TOR switch, all the way to the processors inside the servers.

If silicon photonics is ever going to make it big in what are other­wise all-electronic systems, there will have to be compelling technical and business reasons for it. The components must solve an important problem and greatly improve the overall system. They must be small, energy efficient, and super-reliable, and they must move data extraordinarily fast.

Today, there is no solution that meets all these requirements, and so electronics will continue to evolve without becoming intimately integrated with photonics. Without significant breakthroughs, fat photons will continue to be excluded from places where skinny electrons dominate system function. However, if photonic components could be reliably manufactured in very high volume and at very low cost, the decades-old vision of fiber-to-the-­processor and related architectures could finally become a reality.

We’ve made a lot of progress in the past 15 years. We have a better understanding of photonic technology and where it can and can’t work in the data center. A sustainable multibillion-­dollar-per-year commercial market for photonic components has developed. Photonic interconnects have become a critical part of global information infrastructure. However, the insertion of very large numbers of photonic components into the heart of otherwise electronic systems remains just beyond the edge of practicality.

Must it always be so? I think not.

About the Author

Anthony F.J. Levi is a professor of electrical engineering and physics at the University of Southern California.

Silicon Photonics Stumbles at the Last Meter syndicated from https://jiohowweb.blogspot.com

[pleasingwords]

Heavenly War - Episode 2

The farm was small, the road leading to it barely distinguishable from the surrounding rocky hillsides. It seemed like a place unaccustomed to visitors. But today a caravan had come to visit, selling a very specific good.

“I’m not sure I need more labor right now,” the farmer told the slavers, pacing before their lineup. “The harvest’s been poor, and money’s tight.”

“Oh, isn’t that always the way,” a sympathetic voice offered from the row of assembled slaves.

“How about this one, farmer Jun?” the slaver said, pausing next to the voice’s source, an almost cadaverously thin man. His neighbor was half his height, and considerably stouter than the average slave. “He’s the perfect size for crop harvests,” the slaver suggested, “and as a special offer, I’ll toss in his friend for free!”

“My name is Wang,” the thin man said patiently. “And my friend’s name is Zhang, Big Zhang. It’s really not hard to remember.”

“Free?” Farmer Jun asked. His wife stood by the farm’s huts, watching along with a teenage boy.

The slaver grimaced. “You know what, I’ll pay you. Ten dan off the short one’s price if you take the skinny one too.”

“Unappreciated,” Wang said. “Typical.”

“Done,” Jun said, shaking the slaver’s hand. The slaver’s men unhooked his purchases from their chains. “Come along, now. No time for rubbernecking, Lo Po, Jat Ji. There’s much to do.”

The teenage boy, watching, found Big Zhang gazing at him with equal intensity. He turned away, shaken.

“You know the routine, nephew,” Farmer Jun told the boy a few weeks later. “Take the crops directly to town, take the money directly back. No distractions, no side trips, absolutely no adventures. And don’t be afraid to use the whip to keep the slaves in line.”

“I’m sure they won’t cause any trouble, Uncle,” the teenager told him. “Aside from the complaining.”

“I’m not worried about them,” Jun said. “I’m worried about you!”

The boy rolled his eyes and set out to fetch the ox-cart.

The road to town was long. Normally the boy took used the time to fantasize, imagining far-away adventures and romance. Today he found it difficult to concentrate.

“You really must listen to me, young Tianxing,” Wang said once again, riding on the back of the cart. “We’ve been sent on an important mission. The whole of the kingdom depends on us!”

The boy Tianxing sighed. “Look, Wang,” he said. “You heard my uncle. No side trips, no adventures. I owe Uncle Jun and Auntie Jao a great debt for taking me in and raising me as their own child. I don’t want to disappoint them again!”

Wang drew a breath to continue arguing, then paused. “What’s that?” he asked.

A low horn blast echoed in the distance.

Tianxing’s eyes widened. “Tribesmen, off the northern steppes,” he said. “Their raiding parties use those horns to signal that they’ve found a target. And - “ he paused to listen. “It sounds like they’re coming closer.”

Big Zhang whistled mournfully.

“Are you a great warrior in disguise as a peasant boy?” Brave Wang asked. “Can you defeat an steppe army singlehandedly?”

“I have a bow,” Tianxing said. “I use it to hunt rabbits. One time I shot one from a hundred bu away!”

“We’re doomed,” Wang sighed.

Figures on horseback appeared, cresting the hills to the northwest. One raised a horn to his lips and blew, letting out another long, low blast.

“It’s all right,” Tianxing said. “They might only want our goods, not our lives -”

Big Zhang covered Tianxing’s lips. He pointed to the east.

A curious figure stood there. He wore an elaborate costume, with the legs of a horse and a headpiece shaped like the sun. In his hand was a horn, long and twisted; as Tianxing and the others watched, he brought the horn to the front of his headpiece and blew a long, complex sound.

“Who is that?” Brave Wang whispered. “Is that one of their leaders?”

“I don’t know,” Tianxing whispered back. “His costume - I think that’s a religious outfit of some kind, the face of their sky god. He could be a shaman. But - look!”

The horsemen on the ridge had paused while the shaman played his horn. Now, wheeling their horses, they were leaving, riding back to the north.

Big Zhang tilted his head inquisitively.

“I don’t know what it means,” Tianxing said. “But the shaman is waving. I think he wants - us.”

---

Tianxing and the others found themselves at the entrance of a small, musty cave. Wang tied the ox-cart up outside while Tianxing and Zhang proceeded inward.

“This is a home,” Tianxing said, his voice hushed. “Furniture - not much, and no decorations, but well used. Someone’s been living here for a long time.”

“Yes,” a reply emerged from the shadows. The shaman walked forward, now wearing only a plain brown robe. “Ever since the old wars, against Western Wei. Ever since I brought you here to be fostered with your uncle Jun and aunt Jao. I’ve been watching over you for a long time, young Tianxing.”

Tianxing blanched white. At a loss for words, he didn’t notice at first when Big Zhang walked past him.

“Are you General Gaohuan?” Zhang asked.

Now it was the brown-robed man’s turn to pause. “That’s a name I haven’t heard in a long time,” he said.

Zhang knelt. “I carry a message from the Phoenix Princess Chufung,” he said. “The usurper Wenxuan is bent on exterminating all resistance against him. Even now, his right-hand man General Erzhu is taking the Princess to Red Stone Fort, where she will be tortured until she gives him the location of the rebel base.”

“Please, General Gaohuan. You must help us. You are our only hope.”

Tianxing turned to Zhang, his eyes growing even wider.

“You *speak*?”

[araniladin]

Step into my Parlor

Little short story I wrote, felt like sharing

Teslas parked illegally in front of your apartment would not be a common harbinger of doom, but that day, two of them, red and blue, stood outside the door to my complex.  I had always liked the idea of the car, electric, thumbing its nose at those gas guzzling assholes on the road.  These cars never drive down the roads in this part of town.  I felt a cold chill down my spine seeing them.

I took the steps to the apartment I shared with my partner, three easy flights, holding the foil-wrapped burritos in my hands.  The elevator made a lot of noise when it arrived and could take forever to reach my floor.

The apartment near the stairs housed a couple that could only communicate at loud volumes, but they had chosen for a silence night in.  The pothead who screamed at his video games had taken the day off, odd for an unemployed and agoraphobic man.  The mother of three had found a way to quiet all her toddlers and babies.

And the door to apartment 312 hung open.  Our apartment.

Never trust a quiet apartment floor.

Placing the food down against the wall to protect it, I threw back my shoulders and walked to my open apartment.  My flats whispered against the carpet floor as I strolled into my violated home.

The living room was wrecked, the television face down on the floor, the couch ripped opened, all our games and movies scattered across the floor.  A discarded rope laid near the door, which might explain why two boys had my wife pinned against the floor.

The boys wrecking the place all had that mass that came from having too much time at the gym, perfectly sculpted muscles and the money to buy the clothes to show it off.  Caps with flat brims, black and white t-shirts and beige shorts.  All of them carried guns, oversized pieces that spoke of too much television and not enough time at the range.  Aside from the two in my living room, two more were in the kitchen, and another trashed the bedroom, having a good time with the underwear drawer.  Fucking frat boys.

They must have caught her as she returned from her patrol, as she still wore her red supersuit.  It had strike plates along the torso and legs for protection, making her skinny figure androgynus, although it looked like something had broken her ankle.  Her hood and mask laid across her head askew, exposing her copper colored hair and a bruised cheek.

She spotted me first, and froze.  The Red Blur, as they all knew her on the streets although her friends and I called her Rose, a speedster who protected this part of San Diego from robberies, muggings, sexual assaults, and saved cats trapped in trees, making sure that if someone missed the bus, they were not late.  Someone who cared more for others than for herself.  It’s why I loved her, one of the reasons.  She never came out to me about her powers, although in the eight years we have been married, I had always known.

I closed the door, the sound of the lock sliding in drew the attention of the rest of the household.  Five guns pointed at my face, Rose whimpering as the boy on top of her ground his knee into her spine.

“Told you there was another!” One of the boys said.  He had a tan so orange it had to be fake.  “This freaky bitch is also a faggot, I told you, Carl!”

The boy digging his knee into Rose’s back rolled his eyes.  He had a boater’s tan with a wispy few hairs on his chin, a failed attempt at a beard.  “Thank you for the observation.  Hey, fatass, how about you take a seat, and we’ll get to you after we finish off with your paramour here.”

This is why I never wear sweaters.  People always mistake my size for weight.  It could also be that they dislike me looking down at them and calling me fat saved their egos.  “How about you get off my partner, and I let all of you walk out of here alive?”

They all laughed.  “Listen lady, we have the guns, and we have the super on the ground.”  Carl said, pressing harder down with his knee till Rose gasped out a breath.  “I do not believe that you have any agency here.”

“And what makes you think she is the only one with powers here?”  Mouths dropped open as my face rippled.  Even Rose looked aghast.  We all have secrets.

“Now, get off my wife, get out of here, and you live, last chance.”

“Supers don’t murder, everyone knows that,” Carl sneered, that knowledge putting steel into his spine.

“Who ever said I was a super?”

Carl’s eyes widen the split second before he fired, everyone else in the room following him.  As they fired, I became we. Bullets struck my clothes, the walls behind me, but bullets are really inefficient means of killing off a swarm of spiders.  It does, however, piss off said spiders.

We skittered around to the kitchen, the two boys in there jumping onto the counter as they fired at the floor.  Their guns clicked empty, and we swarmed over them.  Being six and a half feet tall, and about 220 pounds, we became a lot of spiders. They stomped, swatted, and ripped us off by the handfuls, means of murdering us that hurt as much as the bullets.  Billions of small bites meant lots of small doses of toxin.  Orange boy choked on his own swollen tongue while his partner in the kitchen started to convulse as his nerves were eaten away.

The boy in the bedroom bolted for the door.  When he reached for the lock, we stopped hiding in it, crawling over his hand.  Skittering up his arm, under his shirt, over his neck and we dived into his mouth.  He died choking on us, sixty four spiders crawling down his windpipe.

The other boy, not Carl, leaped out the window.  It shattered around him.  A heavy thump. The car alarm signalling point of impact.

Carl placed his gun against Rose’s head and pulled the trigger.  It clicked empty.

We gathered in front of him, pulling back into a form that had terrorized the East Coast ten years back.  I stared down at Carl through eight eyes.  Three pairs of hairy hands grabbed him and lifted him off Rose.  “I told you, you should have left.”  Large, articular fangs slurred my speech, spraying venom and spit onto his face.  

The front of his beige shorts started to darken, and the smell of urine filled the apartment.  “You’re-you’re Lady Arachnid,” Carl croaked out.

“Thanks for the observation,” I mocked as I hugged him.  Inside my embrace, I became billions again, swarming over him, consuming him.  He tripped over the fallen television and through the open window.

Tattered remains of his body fell from the window, landing next to his unmoving friend.

We became me again, towering computer tech,white hair tumbling over my bare shoulders, my eyes black, the coloring I had when I stalked the world, before I went mundane.

Taking a deep breath, I turned around and knelt at Rose’s feet.  She watched me, eyes full of fear, but when I reached out, she didn’t flinch away from my touch.  “I’m sorry you had to find out that way.”

She sputtered, her face moving from fear to anger to embarrassment.  “I had the biggest crush on you in college.”  Her face matched the red of her suit.

I blinked.  “You are not mad at me for never telling you?”

“My wife is a super villian, my secret is out, and I’m trying not to think about the fact that you killed five guys in our living room,” she giggled, manic as tears streamed down her cheek.  “I have no idea what I feel right now.”

“Well, technically, I only killed four of them and I always knew you were a super,” I said as I sat next to her.  After a moment she shifted into my lap.  Giggling tears fell onto my chest.  “Remember when we started taking Krav Maga classes? It helped hide your bruising from others, the sewing classes that I backed out of first and let you lie about going to?”  She shifted away as if in shame.  “I knew, but I supported you.”

“Why, was I your chance for redemption? Support the hero to make up for what you did?”  The venom in her voice hurt.

“No, I did it cause I loved you.  I...I planned to hide what I was for as long as I could before paying that price.”  Saying it outloud made it sound ridiculous even to me.

Pulling off her hood, she finally looked at me.  “You never hide what you do, you’ve always owned up to it.”

I shrugged.  “Admitting that I forget to pay the phone bill is one thing, admitting I killed a bunch of capitalist is on a whole other scale.”

“Well, they kinda deserved it,” she muttered. “And well, this was self defense, they broke in here, and planned on...hurting me. Is this what shock feels like?”

“Let us get you out of that suit and I’ll take you to the hospital.”  The sounds of sirens far off turned us both towards the window.  “Or we can let the police do that.”

The suit came apart easily, panels designed to be replaced if damaged without having to resew the whole suit.  Much better than a certain black leotard painted with white webbing.  I grabbed sweats from the bedroom and helped Rose into those.  I stuffed the suit into her hidden compartment in the closet.

“Maybe you should also get dressed and, maybe change back into your normal hair color?”  Rose suggested as she ran a hand though my white hair.  “Although that is really, really sexy.”

Smirking, I became we, and flowed back into my clothes.  A few minor adjustments, and I looked normal again.  Rose stared with an open mouth.  “You really did pour yourself into your old costume...do you still have it?”

I laughed.  “Ask me after we get you checked out.”

The sounds of police stomping up the stairs warned us as they flooded our floor.

“Wait, is this why you do web design?”

[weightlossfitnesssinfo]

The Relationship Between Injury and Back Pain: Neutral Spine Versus Flexion

As somebody who has sustained two main again accidents early in my lifting profession, I’ve turn out to be extremely engaged within the present analysis on again ache and therapy/prevention protocols. Through this strategy of analysis and evaluation, my place on again ache and its implications for coaching have modified moderately considerably.

  I've seen an abundance of data on again ache that makes definitive claims when in actuality it’s not that clear reduce. The backbone is a extremely complicated construction, and harm mechanisms are on no account easy. This article will not be meant to be prescriptive. The function is to make clear this complicated topic to impart a greater understanding of the mechanisms concerned in again ache and therapy. My place on harm is that it's best to all the time seek the advice of a professional skilled like a bodily therapist. They will be capable to assess your particular person circumstances and prescribe the suitable therapy protocol.

    That being stated, let's dive into again ache and all its distinctive elements.

  Mechanisms for Disc Herniation and Back Pain

Injury will be outlined as a tissue being taken past its purposeful loading capability.1 Whether it’s bone or delicate tissue it’s primarily the identical fundamental premise. For occasion, while you go into an elevator there's a signal that tells you the maximal loading capability of the elevator. Going past that places the metal cables liable to breaking as a result of the burden has exceeded their purposeful loading capability. The physique works in the identical approach.

  In the diagram under you possibly can see the fundamental construction of the discs and the vertebral joints. A disc herniation happens when a fraction of the disc nucleus is pushed out of the annulus and into the spinal canal via a tear or rupture within the annulus. Anterior herniations are very uncommon, with most herniations being posterior or posterolateral, as proven by the pink arrows within the diagram under.

    Tears within the annulus are the commonest posterolateral due to the anterior longitudinal ligament which rests on the entrance of the vertebral column as proven within the diagram under.

    A 2009 systematic evaluation discovered “In people aged 25-55 years, about 95% of herniated discs occur at the lower lumbar spine (L4/5 and L5/S1 level); disc herniation above this level is more common in people aged over 55 years” and “19-27% of people without symptoms have disc herniation on imaging”.2 This is in keeping with what we at present know in regards to the frequent harm/ache websites for powerlifters and bodybuilders.three

  When we take a look at the mechanisms for disc herniation and again ache we will see proof that factors to acute will increase in compressive drive (ie. leaping and touchdown, falling, a heavy barbell in your again, and so forth.),Four excessive repetitions low load flexion/extension motions,5 excessive load flexion/extension motions,5 and flexion-rotation.6 However, disc herniations linked to again ache are moderately unusual and are estimated to be between 2-5%.7 When you flex your backbone, particularly underneath load, it compresses the anterior facet which forces the nucleus of the vertebral disc posteriorly the place the annulus has solely a skinny wall defending it.6 This will not be a direct mechanism for harm however underneath heavy masses and/or excessive repetition it might improve your threat.Four,7 High load compressive forces underneath flexion additionally improve anterior shear which is commonly related to an harm.7 

      A vertebral endplate is a cartilaginous construction vital in sustaining the integrity and features of the intervertebral disc.eight Endplate fractures can happen underneath comparable circumstances as herniations however the price of pressurization/loading appears to have a major affect on fracture price.9 Wade et al (2015) discovered nearly no distinction within the complete quantity of compressive drive required to trigger endplate fractures when evaluating impartial to flexed positions.7 

    Keeping a Healthy Spine

Based on what we’ve reviewed thus far it’s straightforward to see how flexion and rotation, particularly carried out repeatedly and underneath load, play a job in again harm and ache. Unfortunately, it’s not fairly so reduce and dry. Studies have proven the optimistic traits of spinal actions together with flexion for sustaining a wholesome backbone.10,11 Beyond that, disc degeneration is complicated.

  Inconsistencies defining disc degeneration and creating clear distinctions between regular disc degeneration associated to age, genetics, intercourse, and disc degeneration as a result of extreme loading or sports activities follow is troublesome.12 Several research have additionally discovered a powerful genetic affiliation to again ache that disrupts the generally held perception that loading exposures is the first catalyst for again ache.13,14

  One paper discovered that adjustments in compression forces weren't predictive of harm sort to discs and that its failure mechanism could also be linked to fatigue.15 This suggests an adaptive potential that via conscious exposures can improve fatigue resistance growing resiliency. Other research have identified the restrictions to in vitro fashions which are sometimes used within the classical ache/harm mannequin related to flexion, rotation, and compressive forces.

  Researchers have found that “an in-vitro model for studying fluid flow-related intervertebral disc mechanics. During loading, the outflow of fluid occurred, but inflow appears to be virtually absent during unloading. Pro-elastic behavior cannot be reproduced in an in vitro model.”16 Basically which means the research are restricted as a result of in-vitro fashions don’t account for sure adaptive properties of tissues. Spontaneous reabsorption of lumbar disc herniation is an noticed phenomenon that in line with the info happens roughly 66.66% of the time.17 This is yet one more side of the physique's pure capacity to adapt which is commonly underplayed within the anti-flexion debate.

  One research discovered “Total bending cycles have ranged from 4,400 to 86,400” earlier than inflicting partial or full herniations to the posterior annulus.18 From a sensible standpoint, this exhibits that there's a important vary of unpredictability. I don’t doubt that flexion and compression might feed into the harm mechanism. What I query, nevertheless, is the diploma of affiliation that may confidently be reported.

  Even analysis establishing that tissue reworking is a response to compressive loading presents a possible case for deliberately going into flexion underneath particular circumstances comparable to sports activities follow.19 Physical exercise strengthens the vertebrae and the discs doubtlessly lowering your threat of harm.20 The predominance of again accidents occurring within the lumbar backbone brings a brand new layer of complexity to this dialogue since spinal flexion in powerlifting usually happens within the thoracic backbone.

  In truth, the variety of elite dead-lifters that pull with a rounded higher again is on no account small. Beyond that, when an athlete is loaded maximally there'll doubtless be a rise in spinal flexion anyway.21 Even with this prevalence powerlifting nonetheless maintains a comparatively low harm price estimated between 1-5.eight per 1000 hours of coaching.22 It’s doubtless that each side of the talk are proper, however to various levels and in various circumstances.

  I are likely to agree that lumbar flexion might be not the perfect concept when mixed with axial loading. However, I don't imagine flexion, on the whole, is a direct mechanism for harm. You solely have to have a look at sports activities follow that has dynamic flexion/extension like golf, biking, rowing, snowboarding, and snowboarding to know that it’s extra complicated than merely flexion. Beyond that, sports activities that contain the next stage of flexion don't report the next price of again ache.23

  The Body's Adaptability to Repeated Flexion/Extension

Recommendations to keep away from flexion primarily based actions are made because of the analysis that demonstrated herniations and endplate fractures which occurred on the finish of the impartial vary of movement section flexion. The downside with that is that quite a few different examples take the movement segments to the identical finish vary and we don’t see any mechanism for harm. Squats reveal roughly 40 levels of flexion, golf 48% of max flexion, kettlebell swings 26 levels of lumbar flexion, and the listing goes on.24

  So, why can we see a powerful harm mechanism in a single occasion and a weak correlation within the subsequent? I feel it simply reinforces how complicated this topic is and the way extremely particular circumstances and variables can affect the chance and harm outcomes. The adaptability of the physique is a significant factor on this, though it’s vital to notice that your physique's adaptability to repeated flexion/extension will not be infinite. As noticed with a number of different adaptive processes comparable to power, endurance, and hypertrophy we are going to finally run into our higher restrict.25 The downside is that within the case of flexion primarily based actions we don’t know the place that higher restrict is which poses an inherent threat.

  Below is a summarization of the literature on again harm and ache together with some sensible suggestions.

  Low Load Flexion Low load flexion actions like tying your footwear, choosing up your child, taking part in sports activities and the like usually are not issues to be prevented. Full steam forward.

  Low Load Repetitive Flexion I don’t see low load repetitive spinal flexion as a foul factor particularly when you think about the variety of athletes who go into flexion and extension dynamically of their sport. There will not be a rise within the share of again ache or incidence of harm, so I discover it laborious to imagine flexion on this circumstance will increase threat. The caveat to that is if an train causes ache. In this case, regulate the train so it doesn't trigger ache. If this isn't potential then keep away from it a minimum of in the intervening time.

  High Load Flexion In this respect, I help the impartial backbone place. First and foremost, with regards to workouts like squats and deadlifts I don’t see an inherent profit to flexion. So from an effectivity standpoint, impartial spinal place is most often higher for athletic efficiency. Flexion primarily based actions aren’t essentially harmful, however that doesn’t imply they’re inherently protected and it definitely doesn’t make them higher. All issues being equal I might go the protected route and undertake a impartial spinal place when underneath heavy masses.

  I hope the above suggestions are useful in guiding you thru your coaching. Good luck and carry huge!

  References:

1. Jones, Christopher M., et al. “Training Load and Fatigue Marker Associations with Injury and Illness: A Systematic Review of Longitudinal Studies.” Sports Medicine, vol. 47, no. 5, 2016, pp. 943–974., doi:10.1007/s40279-Zero16-0619-5.

2. Jordan, Jo, et al. “Herniated Lumbar Disc.” BMJ Clinical Evidence, BMJ Publishing Group, 26 Mar. 2009.

three. Strömbäck, Edit, et al. “Prevalence and Consequences of Injuries in Powerlifting: A Cross-Sectional Study.” Orthopaedic Journal of Sports Medicine, vol. 6, no. 5, 2018, p. 232596711877101., doi:10.1177/2325967118771016.

Four. Dulebohn, Scott C. “Disc Herniation.” StatPearls [Internet]., U.S. National Library of Medicine, 1 Aug. 2019.

5. Callaghan, Jack P, and Stuart M Mcgill. “Intervertebral Disc Herniation: Studies on a Porcine Model Exposed to Highly Repetitive Flexion/Extension Motion with Compressive Force.” Clinical Biomechanics, vol. 16, no. 1, 2001, pp. 28–37., doi:10.1016/s0268-0033(00)00063-2.

6. Hoogendoorn, Wilhelmina E., et al. “Flexion and Rotation of the Trunk and Lifting at Work Are Risk Factors for Low Back Pain.” Spine, vol. 25, no. 23, 2000, pp. 3087–3092., doi:10.1097/00007632-200012010-00Zero18.

7. Revisiting the Spinal Flexion Debate: Prepare for Doubt.

eight. Moore, Robert J. “The Vertebral Endplate: Disc Degeneration, Disc Regeneration.” European Spine Journal, vol. 15, no. S3, Jan. 2006, pp. 333–337., doi:10.1007/s00586-006-0170-Four.

9. Veres, Samuel P., et al. “ISSLS Prize Winner: How Loading Rate Influences Disc Failure Mechanics.” Spine, vol. 35, no. 21, 2010, pp. 1897–1908., doi:10.1097/brs.0b013e3181d9b69e.

10. Adams, M A, and W C Hutton. “The Effect of Posture on the Fluid Content of Lumbar Intervertebral Discs.” Spine, vol. eight, no. 6, 1983, pp. 665–671., doi:10.1097/00007632-198309000-00013.

11. Holm, Sten, and Alf Nachemson. “Variations in the Nutrition of the Canine Intervertebral Disc Induced by Motion.” Spine, vol. eight, no. eight, 1983, pp. 866–874., doi:10.1097/00007632-198311000-00009.

12. Battié, Michele C. “Lumbar Disc Degeneration: Epidemiology and Genetics.” The Journal of Bone and Joint Surgery (American), vol. 88, no. suppl_2, Jan. 2006, p. three., doi:10.2106/jbjs.e.01313.

13. Varlotta, G P, et al. “Familial Predisposition for Herniation of a Lumbar Disc in Patients Who Are Less than Twenty-One Years Old.” The Journal of Bone & Joint Surgery, vol. 73, no. 1, 1991, pp. 124–128., doi:10.2106/00004623-199173010-00Zero16.

14. Battié, Michele C., et al. “The Twin Spine Study: Contributions to a Changing View of Disc Degeneration.” The Spine Journal, vol. 9, no. 1, 2009, pp. 47–59., doi:10.1016/j.spinee.2008.11.Zero11.

15. Noguchi, Mamiko, et al. “Is Intervertebral Disc Pressure Linked to Herniation?: An in-Vitro Study Using a Porcine Model.” Journal of Biomechanics, vol. 49, no. 9, 2016, pp. 1824–1830., doi:10.1016/j.jbiomech.2016.04.Zero18.

16. Veen, Albert J. Van Der, et al. “Flow-Related Mechanics of the Intervertebral Disc: The Validity of an In Vitro Model.” Spine, vol. 30, no. 18, 2005, doi:10.1097/01.brs.0000179306.40309.3a.

17. Zhong, Ming, et al. “Incidence of Spontaneous Resorption of Lumbar Disc Herniation: A Meta-Analysis.” Pain Physician, U.S. National Library of Medicine, 2017.

18. Contreras, Bret, and Brad Schoenfeld. “To Crunch or Not to Crunch: An Evidence-Based Examination of Spinal Flexion Exercises, Their Potential Risks, and Their Applicability to Program Design.” Strength and Conditioning Journal, vol. 33, no. Four, 2011, pp. eight–18., doi:10.1519/ssc.0b013e3182259d05.

19. Brickley-Parsons, D, and M J Glimcher. “Is the Chemistry of Collagen in Intervertebral Discs an Expression of Wolff's Law? A Study of the Human Lumbar Spine.” Spine, U.S. National Library of Medicine, Mar. 1984.

20. “Physical Activity and the Strength of the Lumbar Spine." LWW.

21. Potvin, J R, et al. “Trunk Muscle and Lumbar Ligament Contributions to Dynamic Lifts with Varying Degrees of Trunk Flexion.” Spine, U.S. National Library of Medicine, Sept. 1991.

22. Montalvo, Alicia M, et al. “Retrospective Injury Epidemiology and Risk Factors for Injury in CrossFit.” Journal of Sports Science & Medicine, Uludag University, 1 Mar. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5358031/#!po=42.5000.

23. Foss, Ida Stange, et al. “The Prevalence of Low Back Pain Among Former Elite Cross-Country Skiers, Rowers, Orienteerers, and Nonathletes.” The American Journal of Sports Medicine, vol. 40, no. 11, Dec. 2012, pp. 2610–2616., doi:10.1177/0363546512458413.

24. Mcgill, Stuart M, and Leigh W Marshall. “Kettlebell Swing, Snatch, and Bottoms-Up Carry: Back and Hip Muscle Activation, Motion, and Low Back Loads.” Journal of Strength and Conditioning Research, vol. 26, no. 1, 2012, pp. 16–27., doi:10.1519/jsc.0b013e31823a4063.

25. Ahmetov, Ildus I, and Olga N Fedotovskaya. “Current Progress in Sports Genomics.” Advances in Clinical Chemistry, U.S. National Library of Medicine, 2015.

  The Relationship Between Injury and Back Pain: Neutral Spine Versus Flexion is courtesy of Weight Loss Fitness

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[technato]

Silicon Photonics Stumbles at the Last Meter

We have fiber to the home, but fiber to the processor is still a problem

Photo: Getty Images

If you think we’re on the cusp of a technological revolution today, imagine what it felt like in the mid-1980s. Silicon chips used transistors with micrometer-size features. Fiber-optic systems were zipping trillions of bits per second around the world.

With the combined might of silicon digital logic, optoelectronics, and optical–fiber communication, anything seemed possible.

Engineers envisioned all of these advances continuing and converging to the point where photonics would merge with electronics and eventually replace it. Photonics would move bits not just across countries but inside data centers, even inside computers themselves. Fiber optics would move data from chip to chip, they thought. And even those chips would be photonic: Many expected that someday blazingly fast logic chips would operate using photons rather than electrons.

It never got that far, of course. Companies and governments plowed hundreds of millions of dollars into developing new photonic components and systems that link together racks of computer servers inside data centers using optical fibers. And indeed, today, those photonic devices link racks in many modern data centers. But that is where the photons stop. Within a rack, individual server boards are still connected to each other with inexpensive copper wires and high-speed electronics. And, of course, on the boards themselves, it’s metal conductors all the way to the processor.

Attempts to push the technology into the servers themselves, to directly feed the processors with fiber optics, have foundered on the rocks of economics. Admittedly, there is an Ethernet optical transceiver market of close to US $4 billion per year that’s set to grow to nearly $4.5 billion and 50 million components by 2020, according to market research firm ­LightCounting. But photonics has never cracked those last few meters between the data-center computer rack and the processor chip.

Nevertheless, the stupendous potential of the technology has kept the dream alive. The technical challenges are still formidable. But new ideas about how data centers could be designed have, at last, offered a plausible path to a photonic revolution that could help tame the tides of big data.

Inside a Photonics Module

Photo: Luxtera

Plug and Play: A silicon photonics module converts electronic data to photons and back again. Silicon circuits [light blue] help optical modulators [bottom row, left] encode electronic data into pulses of several colors of light. The light travels through an optical fiber to another module, where photodetectors [gray] turn the light back into electronic bits. These are processed by the silicon circuits and sent on to the appropriate servers. 

Anytime you access the Web, stream television, or do nearly anything in today’s digital world, you are using data that has flowed through photonic transceiver modules. The job of these transceivers is to convert signals back and forth between electrical and optical. These devices live at each end of the optical fibers that speed data within the data centers of every major cloud service and social media company. The devices plug into switchgear at the top of each server rack, where they convert optical signals to electrical ones for delivery to the group of servers in that rack. The ­transceivers also convert data from those servers to optical signals for transport to other racks or up through a network of switches and out to the Internet.

Each photonics transceiver module has three main kinds of components: a transmitter containing one or more optical modulators, a receiver containing one or more photodiodes, and CMOS logic chips to encode and decode data. Because ordinary silicon is actually lousy at emitting light, the photons come from a laser that’s separate from the silicon chips (though it can be housed in the same package with them). Rather than switch the laser on and off to represent bits, the laser is kept on, and electronic bits are encoded onto the laser light by an optical modulator.

This modulator, the heart of the transmitter, can take a few forms. A particularly nice and simple one is called the Mach-Zehnder modulator. Here, a narrow silicon waveguide channels the laser’s light. The guide then splits in two, only to rejoin a few millimeters later. Ordinarily, this diverging and converging wouldn’t affect the light output, because both branches of the waveguide are the same length. When they join up, the light waves are still in phase with each other. However, voltage applied to one of the branches has the effect of changing that branch’s index of refraction, effectively slowing down or speeding up the light’s wave. Consequently, when light waves from the two branches meet up again, they destructively interfere with each other and the signal is suppressed. So, if you vary a voltage on that branch, what you’re actually doing is using an electrical signal to modulate an optical one.

The receiver is much simpler; it’s basically a photodiode and some supporting circuitry. After traveling through an optical fiber, light signals reach the receiver’s germanium or silicon germanium photodiode, which produces a voltage with each pulse of light.

Both the transmitter and receiver are backed up by circuitry that does amplification, packet processing, error correction, buffering, and other tasks to comply with the Gigabit Ethernet standard for optical fiber. How much of this is on the same chip as the photonics, or even in the same package, varies according to the vendor, but most of the electronic logic is separate from the photonics.

  Photonics Fail: Photonics will never be a real option to transport data from one part of a silicon chip to another. A single optical switch, a ring oscillator in this case, performs the same function as an individual transistor, but it takes up 10,000 times as much area.

With optical components on silicon integrated circuits becoming increasingly available, you might be tempted to think that the integration of photonics directly into processor chips was inevitable. And indeed, for a time it seemed so. [See “Linking With Light,” IEEE Spectrum, October 2001.]

You see, what had been entirely underestimated, or even ignored, was the growing mismatch between how quickly the minimum size of features on electronic logic chips was shrinking and how limited photonics was in its ability to keep pace. Transistors today are made up of features only a few nanometers in dimension. In 7-­nanometer CMOS technology, more than 100 transistors for general-­purpose logic can be packed onto every square micrometer of a chip. And that’s to say nothing of the maze of complex copper wiring above the transistors. In addition to the billions of transistors on each chip, there are also a dozen or so levels of metal interconnect needed to wire up all those transistors into the registers, multipliers, arithmetic logic units, and more complicated things that make up processor cores and other crucial circuits.

The trouble is that a typical photonic component, such as a modulator, can’t be made much smaller than the wavelength of the light it’s going to carry, limiting it to about 1 micrometer wide. There is no Moore’s Law that can overcome this. It’s not a matter of using more and more advanced lithography. It’s simply that electrons—having a wavelength on the order of few nanometers—are skinny, and photons are fat.

But, still, couldn’t chipmakers just integrate the modulator and accept that the chip will have fewer transistors? After all, a chip can now have billions of them. Nope. The massive amount of system function that each square micrometer of a silicon electronic chip area can deliver makes it very expensive to replace even relatively few transistors with lower-­functioning components such as photonics.

Here’s the math. Say there are on average 100 transistors per square micrometer. Then a photonic modulator that occupies a relatively small area of 10µm by 10µm is displacing a circuit comprising 10,000 transistors! And recall that a typical photonic modulator acts as a simple switch, turning light on and off. But each individual transistor can act as a switch, turning current on and off. So, roughly speaking, the opportunity cost for this primitive function is 10,000:1 against the photonic component because there are at least 10,000 electronic switches available to the system designer for every one photonic modulator. No chipmaker is willing to accept such a high price, even in exchange for the measurable improvements in performance and efficiency you might get by integrating the modulators right onto the processor.

The idea of substituting photonics for electronics on chips encounters other snags, too. For example, there are critical on-chip functions, such as memory, for which photonics has no comparable capability. The upshot is that photons are simply incompatible with basic computer chip functions. And even when they are not, integrating a competing photonic function on the same chip as electronics makes no sense.

Data-Center Design

Today (Left): Photonics slings data through a multitiered network in the data center. The link to the Internet is at the top (core) level. Switchgear moves data via optical fibers to top-of-rack (TOR) switches, which sit atop each rack of servers.

Tomorrow (Right): Photonics could facilitate a change in data-center architecture. Rack-scale architecture would make data centers more flexible by physically separating computers from their memory resources and connecting them through an optical network.

That’s not to say photonics can’t get a lot closer to processors, memory, and other key chips than it does now. Today, the market for optical interconnects in the data center focuses on systems called top-of-rack (TOR) switches, into which the photonic transceiver modules are plugged. Here at the top of 2-meter tall racks that house server chips, memory, and other resources, fiber optics link the TORs to each other via a separate layer of switches. These switches, in turn, connect to yet another set of switches that form the data center’s gateway to the Internet.

The faceplate of a typical TOR, where transceiver modules are plugged in, gives a good idea of just how much data is in motion. Each TOR is connected to one transceiver module, which is in turn connected to two optical fibers (one to transmit and one to receive). Thirty-two modules, each with 40-gigabit-per-second data rates in each direction, can be plugged into a TOR’s 45-millimeter-high faceplate, allowing for as many as 2.56 terabits per second to flow between the two racks.

But the flow of data within the rack and inside the servers themselves is still done using copper wires. That’s unfortunate, because they are becoming an obstacle to the goal of building faster, more energy-efficient systems. Photonic solutions for this last meter (or two) of interconnect—either to the server or even to the processor itself—represent possibly the best opportunity to develop a truly high-volume optical component market. But before that can happen, there are some serious challenges to overcome in both price and performance.

So-called fiber-to-the-processor schemes are not new. And there are many lessons from past attempts about cost, reliability, power efficiency, and bandwidth density. About 15 years ago, for example, I contributed to the design and construction of an experimental transceiver that showed very high bandwidth. The demonstration sought to link a parallel fiber-optic ribbon, 12 fibers wide, to a processor. Each fiber carried digital signals generated separately by four vertical-cavity surface-emitting lasers (VCSELs)—a type of laser diode that shines out of the surface of a chip and can be produced in greater density than so-called edge-emitting lasers. The four VCSELs directly encoded bits by turning light output on and off, and they each operated at different wavelengths in the same fiber, quadrupling that fiber’s capacity using what’s called coarse wavelength-division multiplexing. So, with each VCSEL streaming out data at 25 Gb/s, the total bandwidth of the system would be 1.2 Tb/s. The industry standard today for the spacing between neighboring fibers in a 12-fiber-wide array is 0.25 mm, giving a bandwidth density of about 0.4 Tb/s/mm. In other words, in 100 seconds each millimeter could handle as much data as the U.S. Library of Congress’s Web Archive team stores in a month.

Data rates even higher than this are needed for fiber-to-the-processer applications today, but it was a good start. So why wasn’t this technology adopted? Part of the answer is that this system was neither sufficiently reliable nor practical to manufacture. At the time, it was very difficult to make the needed 48 VCSELs for the transmitter and guarantee that there would be no failures over the transmitter lifetime. In fact, an important lesson was that one laser using many modulators can be engineered to be much more reliable than 48 lasers.

But today, VCSEL performance has improved to the extent that transceivers based on this technology could provide effective short-reach data-center solutions. And those fiber ribbons can be replaced with multicore fiber, which carries the same amount of data by channeling it into several cores embedded within the main fiber. Another recent, positive development is the availability of more complex digital-­transmission standards such as PAM4, which boosts data transmission rates because it encodes bits on four intensities of light rather than just two. And research efforts, such as MIT’s Shine program, are working toward bandwidth density in fiber-to-the-processor­ to demonstration systems with about 17 times what we achieved 15 years ago.

These are all major improvements, but even taken together they are not enough to enable photonics to take the next big leap toward the processor. However, I still think this leap can occur, because of a drive, just now gathering momentum, to change data-center system architecture.

Today processors, memory, and storage make up what’s called a server blade, which is housed in a chassis in a rack in the data center. But it need not be so. Instead of placing memory with the server chips, memory could sit separately in the rack or even in a separate rack. This rack-scale architecture (RSA) is thought to use computing resources more efficiently, especially for social media companies such as Facebook where the amount of computing and memory required for specific applications grows over time. It also simplifies the task of replacing and managing hardware.

Why would such a configuration help enable greater penetration by photonics? Because exactly that kind of reconfigurability and dynamic allocation of resources could be made possible by a new generation of efficient, inexpensive, multi-terabit-per-second optical switch technology.

Photo: Anthony F.J. Levi

Past Perfect: We’ve had the technology to bring optical fiber directly to the processor for more than a decade. The author helped conceive this 0.4-terabit-per-second-per-millimeter demonstrator more than 15 years ago.

The main obstacle to the emergence of this data-­center remake is the price of components and the cost of their manufacture. Silicon photonics already has one cost advantage, which is that it can leverage existing chip manufacturing, taking advantage of silicon’s huge infrastructure and reliability. Nevertheless, silicon and light are not a perfect fit: Apart from their crippling inefficiency at emitting light, silicon components suffer from large optical losses as well. As measured by light in to light out, a typical silicon photonic transceiver experiences greater than a 10-decibel (90 percent) optical loss. This inefficiency does not matter much for short-reach optical interconnects between TOR switches because, at least for now, the silicon’s potential cost advantage outweighs that problem.

An important cost in a silicon photonics module is the ­humble, yet critically important, optical connection. This is both the physical link between the optical fiber and the transmitter or receiver chip as well as the link between fibers. Many hundreds of millions of such fiber-to-fiber connectors must be manufactured each year with extreme precision. To understand just how much precision, note that the diameter of a human hair is typically a little less than the 125-µm ­diameter of a ­single-mode silica glass fiber used for optical inter­connects. The accuracy with which such single-mode fibers must be aligned in a connector is around 100 nm—about one one-thousandth the ­diameter of a human hair—or the signal will become too degraded. New and innovative ways to manufacture connectors between fibers and from fiber to transceiver are needed to meet growing customer demand for both precision and low component price. However, very few manufacturing techniques are close to being inexpensive enough.

One way to reduce cost is, of course, to make the chips in the optical module cheaper. Though there are other ways to make these chips, a technique called wafer-scale integration could help. Wafer-scale integration means making photonics on one wafer of silicon, electronics on another, and then attaching the wafers. The paired wafers are then diced up into chips designed to be nearly complete modules. (The laser, which is made from a semiconductor other than silicon, remains separate.) This approach cuts manu­facturing costs because it allows for assembly and production in parallel.

Another factor in reducing cost is, of course, volume. Suppose the total optical Gigabit Ethernet market is 50 million transceivers per year and each photonic transceiver chip occupies an area of 25 square millimeters. Assuming a foundry uses 200-mm-diameter wafers to make them and that it achieves a 100 percent yield, then the number of wafers needed is 42,000.

That might sound like a lot, but that figure actually represents less than two weeks of production in a typical foundry. In reality, any given transceiver manufacturer might capture 25 percent of the market and still support only a few days of production. There needs to be a path to higher volume if costs are really going to fall. The only way to make that happen is to figure out how to use photonics below the TOR switch, all the way to the processors inside the servers.

If silicon photonics is ever going to make it big in what are other­wise all-electronic systems, there will have to be compelling technical and business reasons for it. The components must solve an important problem and greatly improve the overall system. They must be small, energy efficient, and super-reliable, and they must move data extraordinarily fast.

Today, there is no solution that meets all these requirements, and so electronics will continue to evolve without becoming intimately integrated with photonics. Without significant breakthroughs, fat photons will continue to be excluded from places where skinny electrons dominate system function. However, if photonic components could be reliably manufactured in very high volume and at very low cost, the decades-old vision of fiber-to-the-­processor and related architectures could finally become a reality.

We’ve made a lot of progress in the past 15 years. We have a better understanding of photonic technology and where it can and can’t work in the data center. A sustainable multibillion-­dollar-per-year commercial market for photonic components has developed. Photonic interconnects have become a critical part of global information infrastructure. However, the insertion of very large numbers of photonic components into the heart of otherwise electronic systems remains just beyond the edge of practicality.

Must it always be so? I think not.

About the Author

Anthony F.J. Levi is a professor of electrical engineering and physics at the University of Southern California.

Silicon Photonics Stumbles at the Last Meter syndicated from https://jiohowweb.blogspot.com